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A comment on Chinese city to launch man-made moon to light up skies. Parent comment

Re:Chinese city to launch man-made moon to light up skies by M_Bakhtiari on Friday October 19, 2018 @02:49AM (#18254662)
In this case a pair of satellites in a Tundra orbit [1] inclined to spend most of its time over this particular city seems like the right orbit for the job (as silly as it is to light a city by satellite), which is why I was curious to get an explanation behind the sweeping statement that geosynchronous (not geostationary in particular) orbits had to be in a line along the equator.

1. https://en.wikipedia.org/wiki/Tundra_orbit

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Re:Chinese city to launch man-made moon to light up skies by QuotedForTruth on Friday October 19, 2018 @09:44AM (#18256645)
Oh thats interesting. I hadn't heard of Tundra orbits. Wiki says 2 can provide continous coverage over an area. Wouldnt 1 be enough to act as a moon then? You only need it for half of the day and their period is 1 day right?
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Re:Chinese city to launch man-made moon to light up skies by M_Bakhtiari on Monday October 22, 2018 @03:17AM (#18272773)
The problem with using just one is that geosynchronous orbital periods are one sidereal [1] day, not one solar day. So depending on the time of the year, the satellite would be in position in the wrong half of the day. On the other hand a satellite in Tundra orbit spends not half but more than half of its time in the designated area. Maybe a good compromise orbit could be found.

1. https://en.wikipedia.org/wiki/Sidereal_time

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